Basic Processes Horsepower (HP)

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1 Basic Processes If you're completely new to woodworking, the machines must seem overwhelming. If you have a little experience, you already understand that they are surprisingly safe, and quite easy to use. Let's begin with what is the heartbeat of most shops, the table saw. There are six types of small table saw: bench-top, jobsite, contractor, hybrid, cabinet and sliding. There are also a few (mostly European) saws that have jointers or planers built in, but for now let's stick with the basics. A bench-top saw is for very small work. It's ideal for on-site installations of trim, or small hobby work such as building birdhouses. It is not safe to rip large pieces of plywood or long boards on a benchtop saw, even if it is clamped or screwed to a base. The table is too short and narrow, the motor is underpowered, the blade is too small (often less than 10" dia.), and the fence is too short and low. A jobsite saw is a 10" bench-top model with a factory leg set, which often folds up and/or comes with wheels. Some of them have a Horsepower (HP) If you're shopping for power, look at the amperage and voltage of a motor rather than the horsepower. Some manufacturers have very strange ways of determining HP, so you probably won't be comparing apples to apples. But if you multiply the amps by the volts (the result is watts), you'll be able to compare motor power. For example, a 110V motor that draws 20 Amps (2200 watts) uses the same amount of power as a 220V motor at 10 Amps. Voltage is essentially the intensity or strength of electricity, while amperage described the size or volume of the current. A third factor, resistance, which is measured in ohms, tells you what the limits of the delivery system are. lot of power and are really well engineered. The more expensive ones are targeted at professional carpenters, and they are surprisingly rugged and versatile. Read the manuals online before buying, and take any manufacturer's warnings about capacity limitations seriously. The biggest limitation will probably be rip width: that is, the distance from the blade to the fence. Some models offer add-on table extensions, and if you go this route, it is advisable to permanently mount the saw on a very substantial base. The last thing you need is a saw tipping when a sheet of plywood passes the equilibrium point.

2 Contractor saws used to be no-frills with an open steel leg set. Over the years, manufacturers have added a number of features such as enhanced fences, dust bags and riving knives. The motor on a contractor saw is attached to the bottom of the table. Hybrid saws come with a cabinet (enclosed base) and sometimes more power and a larger table than a contractor saw, but the motor is still attached to the underside of the table. That can be a real pain when it comes to fine-tuning it, to get the blade to line up properly with the miter gauge slots. Dust collection can be easier on a hybrid than a contractor model, because of built-in ports. Cabinet saws are big and heavy and almost always stay in the woodshop. They don't often visit the jobsite. Most offer either 220V single phase or 3-phase power options, although there are some that only come in a 110V model. The motor on a true cabinet saw is attached to the cabinet. Adjusting the top to align it with the blade is a lot simpler: usually, it's just a matter of slightly loosening four bolts, making the needed adjustment and re-tightening. If you're setting up a small, professional cabinet shop, then it's worth looking at a sliding table saw. These are either built with a sliding table instead of the left-hand wing, or else an aftermarket table can be attached to a regular cabinet saw. A few small bench-top or jobsite saws are available with very limited sliding tables. And the table saws in large professional cabinet shops have fully automated sliding tables that are CNC controlled with keypads, rather than having somebody physically push a table along. The biggest advantage to those is that they handle large sheet stock efficiently and safely. They also offer great repeatability. There is a less expensive solution than buying an automated slider. We attached an Excalibur sliding table to our Grizzly cabinet saw many years ago, and it has served us very well. Today (2015), the Excalibur sells for about $1,500. But if I had to do it over, I would forego the slider and buy a vertical panel saw from a company such as Saw Trax (sawtrax.com) or Safety Speed Cut (safetyspeed.com, shown at left) for about the same money, mostly because of the footprint. 2

3 Using a Table Saw Before you plug in your new saw, do a couple of simple safety checks. The best way to do those is to use a dial micrometer with a magnetic base as shown above ($40-$50 from sources such as Grizzly or Sears). Tape measures are too flexible and erratic to get a really fine reading, and the printed increments on them are too far apart. Note that the photograph above was taken from the back of the saw, only because that's the way this micrometer worked best. Here's how it works. Start with a scrap of 180-grit sandpaper and make sure the miter gauge slot is free of dirt, grit and even small casting irregularities. If there are significant nubs, use a fine metal file to remove them without distorting the slot itself. Pop a piece of tight fitting scrap wood in the clean miter gauge slot. Tight just means to the point where there is no wobbling. You're doing this because you want the micrometer's base to register off the same plane at the front and back of the blade. Raise the blade and use a permanent marker to leave a small dot on the edge of the blade body, between two teeth. Lock the micrometer to the table and take a reading at the dot. Then rotate the blade a half turn (180 degrees) and, without moving the micrometer, take a second reading. This will tell you if the arbor is true or the 3

4 blade is warped. If the reading is more than 2/1000", something needs fixing. It could be as simple as dirt where the blade meets the arbor flange. Just remove the blade, clean everything, replace it and take another pair of readings. If it's still off, remove the blade and lay it flat on the cast iron table. Touch it gently. Does it wobble? Use a magnifying glass to see if there are gaps. If the blade is flat, then use the micrometer to check run-out in the arbor. To do that, remove the insert and take readings from above, at the tip of the arbor, 180 degrees apart, with the micrometer base attached to the table. If the arbor is off more that 2/1000", call the saw manufacturer for a suggestions or a remedy. Assuming the arbor is within acceptable tolerances, the next reading will check whether the blade is aligned to the miter gauge slots. Set it up as shown in the photo, with the micrometer base snug against the piece of wood in the left-hand slot. Let the micrometer's pin touch the body of the blade, and not a carbide tip. Take readings at the front and back of the blade. If they are within 3/1000" of each other, you're good to go. If not, make an adjustment to the tabletop or the motor mount (see your saw's manual). Repeat the process for the fence. Working off the right-hand miter gauge slot, and with the fence locked in place, take a reading at the front and another at the back of the table. If they are within 3/1000" of each other, all is good. If not, read the manual and adjust the fence. Types of Blades There are three categories of blades, and two measures of thickness. A blade can be designed for crosscutting (across the grain), ripping (along the grain), or a combination of these two. And it can be a full 1/8" thick, or 'thin kerf'. A crosscut blade will have a lot of small teeth, like the one shown at left. An old friend of mine, Tom Walz, who owns a company called Carbide Processors in Tacoma, Washington, designed this one. The tips are cermet, a combination of ceramic and metal. It's a relatively expensive blade, but it will last an awfully long time because it runs so cool. 4

5 A ripping blade will have a few very large teeth. And a combination blade, which is the most popular option for most table saws, will be somewhere between. We generally run a really good combination blade in the table saw, and a crosscut in the miter saw. Our favorite blades are The World's Best Blade (crosscut) from Carbide Processors; the Woodworker II (combination) from forrestblades.com; and the Micro-Kerf 40 (combination, shown below) from Wisconsin-based totalsawsolutions.com. All of the blades we use in our shop, with one notable exception (the Micro-Kerf), are a full 1/8" thick. Most of the cheap blades at the big box stores will say 'thin kerf' on them, as if that is something desirable. In my opinion, it usually means that the manufacturer used less material and made a less expensive, lightweight product. We have found that some thin kerf blades can actually flex under strain. The only real advantage claimed for them that they save a tiny bit of wood doesn't make sense to me for an average woodworker. If you were sawing millions of board feet a year, then that's an issue. 5

6 But for even small professional shops, the saving in material is so negligible as to be ludicrous. The other claim is that they cause a little less resistance in underpowered saws. Well, if your saw doesn't have enough power to do the job safely, it's time to go shopping. Pushing a blade or a motor to its limits can be dangerous, and expensive. The one thin kerf blade we love is the Micro-Kerf. This is an absolutely exquisite piece of engineering, and its thin profile has nothing to do with saving a few bucks in manufacturing. According to the maker, it's actually the thinnest cutting carbide-tipped saw blade on the market (see the photo on page 5). But it comes with two builtin blade stabilizers that make it rigid, and true. It delivers a glue-ready cut that almost never needs to be sanded. Though it's a little more expensive, this is absolutely full value for your money. Tips, Sets, Hooks and Other Funny Words There are literally hundreds of different blade tip designs on the market. A tip is either part of the blade, or a carbide or cermet insert that is brazed to the blade. The dip behind each tip is called a gullet. In blades, the word 'set' refers to how much wider the tip is than the thickness of the blade. By making the tips wider, the body of the blade doesn't contact the wood and cause heat, resin buildup, or binding. The word predates carbide tips. In centuries past, a saw maker would tap on each tooth and bend it a little. The first would bend to the left, the next to the right, and so on all around the blade. The action of bending the tip was called 'setting'. Today, the most common set is still the one described above, which is shown at left. Note that every other tooth leans in a different direction (left or right). It's called an alternating top bevel, or ATB. 6

7 Some specialty blades are designed with a single set (all the tips bend one way), but these are for specialized manufacturing processes and materials. A few manufacturers make patterned sets, where a few teeth bend one way, and the next few bend the other. The majority of handsaw, circular, or band saw blades will have an ATB. With carbide tips, the top of the tip picks up this action. One tip will be ground with a very slight angle to the left, and the next will slope to the right. Rather than bending teeth, manufacturers now grind tips to gain the same benefit. One advantage to this is that there is a tiny point on each tooth, and these hit the wood first. That helps deliver a cleaner cut, especially when cutting across the grain or in veneered plywood. The tips in effect 'score' the surface, separating the topmost fibers to they don't tear out and leave a ragged edge. Sometimes the ATB teeth are interrupted by a third element, a raker. You might have a left, a right, another of each, and then a flat top grind (FTG), which cleans or 'rakes' the bottom of the cut. Usually, the manufacturer will gently chamfer, or angle, the corners of these FTG tips, so they don't undo the work done by the ATB tips. And yes, the ATB tips wear down faster than the FTG ones, because a smaller portion of the tip is doing a larger portion of the work. A hook describes the angle at which the face of the tooth or tip meets the wood. The more the tip leans forward, the more aggressive it is. By leaning it backwards (giving it a 'negative' hook), the manufacturer gives us a little more control on the saw when we use it. The wood is fed just a little slower, and we have a millisecond longer to respond to changes. A simplified rule of thumb might be this: positive hooks are handy on rip cuts (few teeth), where you are running a long piece of wood with the grain. Negative hooks work better on cross-grain cutting (lots of teeth) where you need to slow things down to avoid tear-out. Gullets, the dips behind the teeth, vary a lot. The bigger the tooth is, the bigger the gullet. They allow the tip to cut without accumulation: it's not cutting the same material over and over again, because the waste has somewhere to go. By providing this relief valve, the saw maker helps the blade avoid chatter and heat. I like to run my table saw blades so that the bottom of the gullet is just above the wood (maybe ¼" or so). This means that all of the blade's geometry is in play, but the blade is low (not too much of it is exposed, to cause excessive binding or injury). 7

8 Running A Table Saw We've talked about blades, safety devices and tuning up the saw (getting the blade and fence to line up with the miter gauge slots). It's amazing how many intelligent people don't check that they have plenty of room after the blade for whatever operation they're performing. They get 90% through the cut and the wood hits a wall, post, other machine, cabinet or some other obstacle. This can be pretty dangerous, as they often ease up their grip on the work and it starts to wander, and then catches and kicks back. You'll need plenty of room to maneuver before the blade, too. A lot of people setting up shops in garages position the front of the saw about a foot in from the overhead door, and they just raise the door before making a cut. This gives them all the room they need. If your shop floor is painted concrete or varnished hardwood (or has the equivalent slipperiness, such as laminate flooring or linoleum), then watch out for sawdust. It can make the floor as slippery as an ice rink, and Murphy's Law says that you'll probably only discover this when you're guiding a full sheet of thick plywood into the blade and begin to lose your balance. Most pros running one-man shops will invest in a vertical panel saw to slice up sheet goods into manageable sizes before trimming the much smaller pieces to size on the table saw. A pair of sawhorses and a portable circular saw will work, too. The process is known as reduction, and big shops routinely did this before the advent of large CNC routers that can nest (optimize get the most efficient yield from) sheets automatically and delivery absolutely precise parts in a single operation. If possible, use a safer method to reduce the sheet stock before running full or large sheets across a table saw. (If your saw is equipped with a sliding table, then that changes the rules.). Sorry to sound like your Mom, but tuck your shirt in and roll up your sleeves before operating a table saw or any other woodshop machine. A lot of injuries happen when the end of a sleeve or a piece of jewelry such as a necklace gets wrapped up in the blade and pulls the operator in. It happens in a millisecond. Don't wear rings or watches in the shop, either. But do wear safety glasses: I always order my regular glasses with safety frames and lenses, and that way I never forget to change glasses. Nowadays, manufacturers offer lots of nice looking safety frames that can be worn all day. 8

9 An out-feed table is essential. Rollers on stands simply aren't large or sturdy enough, if you're building cabinets or large furniture. They work well for moldings and trim, or with a miter saw or router table. But a table saw needs more support with sheet goods. The out-feed table should be a hair lower than the table saw table (less than 1/8" difference, if possible), and the front edge of the table, nearest the saw, should be chamfered. That means it should have an angle milled on it that acts like a tiny ramp, so that parts coming off the saw don't get hung up on. The table should be about the size of the table saw, maybe three or four feet in each direction, so that the fulcrum (tipping point) is after the blade. That will stop the trailing edge of a sheet of plywood from lifting off the table before it has cleared the blade. Both tabletops need to be in the same plane. If a board is too big and tippy, chop it up with a portable saw first to make manageable pieces. And if the work is so small it's making you nervous, perhaps the band saw would be better. Stance is very important around table saws. You must be balanced and comfortable, and plan for movement before it becomes necessary. You don't want to be unsteady at any stage of the cutting process. Reaching out to steady oneself, or adjusting a stance while feeding the blade can both lead to problems. Sweep the floor. Regularly. Never, ever place anything on the table saw to the left (blade side) of the fence, if you're not cutting it. If you forget that a tape measure, pencil, tri-square or wooden part has been left there, it will migrate to the blade and become airborne when the saw is turned on. If you train yourself in this, it will feel strange and wrong if you absentmindedly place something there. My parents are both long gone, but I hear their voices when I do this awful thing Use the right blade. A combination blade will do most of the daily work in a shop, but there are times when a specialty blade is necessary. If you're ripping a lot of stock for moldings, then buy a rip blade. If you're crosscutting a lot of veneered plywood to build a kitchen, then pop in a plywood blade. You can tell if the blade is working too hard when you feel resistance, and it begins to burn edges. If you're ripping dense wood such as red oak, and there are burn marks on the kerf or a wisp of smoke in the air, you're pushing your luck. The blade has too many small teeth, or it's dull, or the oak is too thick. If it's a fresh rip blade and you still have problems, then make the cuts in two passes, which will halve the workload for the blade, and the motor. 9

10 If you smell smoke, shut down and clean out the sawdust. A lot of shop fires have begun when resistance caused heat build-up that smoldered overnight and fanned into flames when somebody opened a door, or turned on a dust collector, or something else happened to cause a slight draft. Most right-handed woodworkers prefer a left-tilt table saw. Cutting at an angle will change the way that the force you generate is distributed. On a standard cut, with the blade fully vertical, the operator uses much of his effort forcing wood down and across the table, and just a little bit pushing it against the fence. On an angled cut, those forces are about even because resistance tends to force the wood away from the fence. A lot of woodworkers dislike working with an angled blade. The path of the teeth somehow feels less predictable when they're not in a vertical plane, and that increases one's feeling of vulnerability. But if you use feather-boards to hold the work down and against the fence (in front of the blade), and a push stick to impel the work across the table, it's a very safe process. If a board wanders away from the fence the farther it gets from you, the fence is probably out of alignment. But it might also be the wood reacting to the cut, or a bent blade, or improper seating of the blade on the arbor. The point is, if something looks or feels wrong, stop and figure it out. Don't be tempted to just finish up this one board When cutting thin plywood parts such as door skins (they're not much more than the thickness of a sheet of veneer) or other very thin materials such as plastic laminate, make sure the edge of the workpiece doesn't slip under the fence and catch. Add an auxiliary fence if necessary, to close the gap between the bottom of the fence and the table. 10

11 If you're going to be working with recycled materials, check every board with a metal detector from companies such as Garrett (garrett.com), Schonstedt (schonstedt.com), Fisher (fisherlab.com), or Rens (metaldetect.com), among others. You don't want to hit old wire, nails or other hardware in the middle of a cut. Harbor Freight and other catalogs sell very inexpensive detectors for occasional use in relatively thin stock. If you're running a small sawmill, check for metal before every single cut. Blades are expensive. (Those are our friends Larry and Druse Kellogg on page 10, checking an ash log for metal.) Green (wet) wood will often bind because it has sap or resins that can heat up and smear the blade. If that happens, the teeth and tips get coated and the blade can no longer slice, so it heats up even more. Cutting other materials on a table saw is not always a great idea Some sheet goods, such as flat diffusers from fluorescent lights, will probably shatter. Those should never be cut on a table saw, unless they are safely sandwiched between two pieces of sacrificial plywood with the edges of the sandwich perfectly aligned and taped. Some products such as thin insulation or flexible foam are just too soft, even in a sandwich, and may wrap around the blade and pull the woodworker toward the teeth. Use common sense, and a utility knife. Using a push stick can be a pain in the butt sometimes, but it's still a whole lot better that a piece of plastic or wood contacts the blade, rather than skin and bone. If something goes wrong, the push stick may smack your hand and hurt like an elephant giving birth, but a bruise or even a broken digit is a lot better than looking through the sawdust for a severed fingertip while trying to stop the bleeding. The exposed part of the blade is less than 4 inches. Your push stick should keep your hand at least this distance away. If it is too long, you lose leverage, so use feather-boards and hold-downs whenever possible, and the stick will have less work to do. The blade, teeth, tips, motor and tabletop dimensions are all determined and known commodities. So, the only variables are the material being cut, and you or, more accurately, the speed at which you feed the material to the blade. If the cut has a lot of tear-out or the saw begins to bog down, you may be pushing too fast especially with veneered plywood or MDF (medium density fiberboard). If the kerf has burn marks, you could be moving too slowly. Of course, some sugary species such as cherry or some of the maples may burn no matter what you do, and that's why we have jointers, planes and sanders. 11

12 Cross-cutting The majority of cuts on a table saw are rips that simply slide against the fence. For cutting across grain, table saw manufacturers supply a miter gauge, and I think that most of these should be instantly recycled for the metal in them. The guide bars tend to be sloppy fits that wobble in the tabletop slot, and the short fence (often no more than six or eight inches wide) is not enough support for the vast majority of crosscuts. You can fix the latter by adding a wooden auxiliary fence, but sloppiness is a whole other issue. The auxiliary fence that most woodworkers add is a straight 1x4 a couple of feet long that is screwed to the front bar of the miter gauge. Run it through the lowered blade to establish a starting point for making measured cuts: just measure left or right from the kerf that the blade left in the auxiliary fence. Attaching 180-grit sandpaper to the front of the fence will usually prevent work sliding left or right as it is being cut. Perhaps a better idea is to invest in a high quality aftermarket miter gauge such as the magnificently engineered Incra Miter 1000 (shown above, and available through incra.com), or a similar top quality item from the Woodhaven or Kreg lines, Osborne's EB-3, the JDS Accu-Miter, or JessEm's fence and gauge system, among others. Most of these offer a system for getting rid of sloppiness in the miter gauge slot, such as the one shown at left on the Incra jig. Simply insert an Allen key and tighten up the cams, one of which is phenolic. If they're too tight and the jig won't slide easily, just back them off a hair. 12

13 Some other miter gauges worth looking at are the Delta , the Dubby, and Woodhaven's DeLuxe (I use this one). Some woodworkers prefer a sled to a miter gauge for cutting across the grain, and for handling small parts. This is a platform, usually made of plywood, with a couple of guides attached to the bottom that slide in the two miter gauge slots. A fence is mounted on the top, along the back edge. Some sleds are quite elaborate, with adjustable fences that allow the user to make cuts at angles other than 90. Others include sophisticated mechanisms for securing work as it is being cut. The one shown here uses Incra hardware for guidance in the miter slots, holding the work and an adjustable stop on the back fence. One safety advantage to using a sled rather than a miter gauge when cross-cutting small parts is that the sled catches offcuts and carries them free of the blade. A table saw's main fence can be used in conjunction with a miter gauge to make several parts that are the same length. However, this can only be done with a spacer block. You can't clamp or hold wood against a miter gauge and slide it through the blade if it is touching the fence as it travels. It's almost guaranteed that the cut-off will bind between the blade and the fence, and kick back. So, clamp a small block of wood to the end of the fence closest to you, and use this as a stop. Butt the work up against it so the length is established for cuts. As you push the work across the table, it will part company with this spacer block before it contacts the blade. Dado Heads These come in two varieties, stacked and wobble. Many countries have regulations about them and some countries won't allow them to be sold. The main reason is that they create a lot of resistance because a very large cutter is passing through the wood, and in many countries the standard table saw is a lot smaller than the average one in the U.S. 13

14 or Canada. Small machines with very little power can't safely handle a dado head. For this reason, many of the small jobsite saws sold in America don't have a long enough shaft to mount a dado head. A stacked dado comes with two blades and one or more chippers. The blades cut clean sidewalls in a dado or groove, and the chippers remove the waste between these cuts. A wobble dado is a less expensive option, where the width of the cut is dialed in on a cam mechanism. There is only one blade, and it is tilted to create a wider path. I personally don't like, trust or use wobble dado heads. However, many people do. I have a few stacked dado sets from reputable suppliers, and I've had them for many years with no complaints. I've used products from Freud, Diablo, Oshlun, DeWALT, CMT, Avanti and other reputable manufacturers, and discovered that you usually get what you pay for. Higher priced sets tend to deliver cleaner cuts, and last a lot longer between sharpenings. Almost any stacked set will handle the workload for an occasional woodworker. As with all tools, professional woodworkers should buy the best they can reasonably afford. One final thought: bury the dado head in an auxiliary fence for rabbets. That is, on a left-tilt saw where the fence is to the right of the blade, the rabbet should be against the fence and the uncut tongue should be to the left of the cutter. This avoids trapping the tongue between the fence and dado head, and it delivers cleaner cuts if you need to make more than one pass because a vertical panel wobbled a bit as it traveled against the fence. 14